In this study, leaf photosynthetic CO2-response curves of Quercus variabilis and Robinia pseudoacacia were measured using a Li-6400XT photosynthetic measurement system in the southern foot of the Taihang Mountain, China. The rectangular hyperbola model (RH), nonrectangular hyperbola model (NRH) andYe model (YZP) were used to fit photosynthetic-CO2 response curves and compare photosynthetic parameters, including the maximum net photosynthetic rate (Amax), the initial carboxylation rate (η), light respiration rate (Rp), CO2 compensation point (CCP) and CO2 saturation point (CSP). Compared with the NRH and YZP models, Amax, η, Rp and CCP obtained by the RH model were higher, and were 59.8%, 128.6%, 133.4% and 19.8% higher than the measured values. The accuracy of the RH model was lower and its relative error was higher than that of the NRH and YZP models.Compared with the RH and YZP models, Amax fitted by the NRH model was higher, and was 11.1% higher than the measured value. η, Rp and CCP fitted by the NRH model were closer to the measured values. CO2 saturation phenomenon of photosynthesis could be simulated by the YZP model, and Amax and CSP were fitted well. Amax, Rp and CCP in the shaded leaves of Q. variabilis were 31.3%, 5.2% and 14.3% lower than those in the sunlit leaves. Amax, Rp and CCP in shaded leaves of R. pseudoacacia were 23.5%, 11.0% and 5.4% more than those in the sunlit leaves. η in the shaded leaves of Q. variabilis and R. pseudoacacia were 6.9% and 7.0% higher than those in the sunlit leaves, respectively. Rp and CCP of R. pseudoacacia leaves had linear relationships with temperature (T) and photosynthetic active radiation (PAR), and η had a significant relationship with stomatal conductance (gs). η of Q. variabilis leaves was linearly correlated with PAR and gs, and CCP was affected by T and relative humidity. Amax of Q. variabilis leaves had significant positive linear relationships with RH and gs.
采用便携式光合仪(Li-6400XT)对太行山南麓栓皮栎、刺槐2个树种叶片光合作用-CO2响应曲线进行测定,利用直角双曲线模型(RH)、非直角双曲线模型(NRH)以及直角双曲线的修正模型—叶子飘模型(YZP)进行曲线拟合,并对3种光合模型的拟合参数(最大净光合能力Amax、初始羧化速率η、光呼吸速率Rp、CO2补偿点CCP和CO2饱和点CSP)进行比较.结果表明: 与NRH和YZP模型相比,RH模型所得的Amax、η、Rp和CCP较高,分别高出实测值59.8%、128.6%、133.4%和19.8%.与RH模型和YZP模型相比,NRH模型拟合得出的Amax较大,高于实测值11.1%,η、Rp和CCP接近于实测值.YZP模型能较好地模拟光合作用对CO2的饱和现象,在Amax和CSP的拟合效果上较好.栓皮栎阴叶的Amax、Rp和CCP比阳叶分别低31.3%、5.2%和14.3%.刺槐阴叶的Amax、Rp和CCP分别高出阳叶23.5%、11.0%和5.4%.栓皮栎、刺槐阴叶的η分别比阳叶高6.9%和7.0%.刺槐叶片的Rp和CCP与温度、光强均具有显著线性关系,η与气孔导度(gs)具有显著线性关系.栓皮栎叶片的η与光强和气孔导度具有显著线性关系,CCP主要受温度和湿度影响.栓皮栎叶片的Amax与相对湿度和gs具有显著的正线性相关关系.
Keywords: Quercus variabilis; Robinia pseudoacacia; photosynthetic parameter; photosynthetic-CO 2 response; shaded/sunlit leaf.